A Programmable Hydrogel Platform with Tunable Phase Transition Temperature and Mechanical Properties for Information...

Area of Science:

• Materials Science
• Polymer Chemistry
• Biomaterials Engineering

Background:

• Precise hydrogel design requires quantitatively linking molecular composition and hierarchy to properties and functions.
• Existing hydrogel systems face challenges in achieving editable and programmable characteristics for advanced applications.

Purpose of the Study:

• To develop a programmable hydrogel system with tunable properties by controlling copolymer composition and physical entanglement.
• To explore the application of this smart hydrogel in information encryption and soft actuators.

Main Methods:

• Copolymerization of N-isopropylacrylamide (NIPAM) with N,N'-dimethylacrylamide (DMAA) and acrylamide (AM), utilizing hydroxypropyl cellulose (HPC) for physical entanglement.
• Tuning the lower critical solution temperature (LCST) by adjusting DMAA content and evaluating mechanical properties (compressive modulus, mechanical loss rate) with varying AM content.
• Fabricating a bilayered hydrogel structure with a modulus gradient for soft actuator development and employing finite element simulation to analyze bending behavior.

Main Results:

• The hydrogel system allowed precise adjustment of LCST between 34°C and 49°C by incorporating DMAA.
• Increasing DMAA content decreased compressive modulus, while AM incorporation enhanced it significantly (16.2 to 24.0 kPa) with low mechanical loss (3.6%).
• Demonstrated applications include temperature-dependent quick response (QR) code encryption and a thermally induced bending soft actuator with a modulus gradient.

Conclusions:

• A simple and rational strategy for designing a smart hydrogel platform with tunable properties and diverse applications was established.
• The developed hydrogel system offers precise control over thermal and mechanical properties, enabling advanced functionalities.
• This research provides a foundation for creating sophisticated hydrogel-based devices for encryption and actuation.